1. Field of the Invention:
This invention relates to an apparatus for the manufacture of flat bread, such as pita bread, having notches disposed therein to provide a preferential tear location and in pita bread, a preferential rupture area to provide a smooth unfaulted exterior thereon as a result of baking, a method of making such flat bread using an apparatus of the type described herein, and flat bread so made.
2. Art Background
There are several types of flat bread which are known today including lavash, and pita bread which is more well known. Pita bread, also known as pocket bread, is a bread of Middle Eastern origin dating back a number of centuries. In general, pita bread comprises a relatively flat bread having a generally rounded or oval shape and typically four to eight inches in diameter and one eighth to three eighths inches in thickness. An important aspect of the pita bread is that as a result of a specific baking process described in more detail below, a pocket or inner chamber is formed which can serve to hold various food ingredients such as meats, grains, vegetables, sauces and the like, both liquid and solid materials. Thus, pita bread is usually stuffed with these components and eaten.
Pita bread is a common staple in middle eastern countries and in recent years has enjoyed considerable and increasing popularity in other areas of the world. This popularity is due in part to the convenience of using pita bread for making a sandwich since the bread, when torn, forms a pocket which may be filled with meat, vegetables, cheese, and other edible material and is also often filled with sauces of various types.
Typically, the user will make a sandwich by tearing the pita bread in half, forming two semi-disks which can each be used to make a sandwich. Alternatively, the pita bread may be torn, cut, or otherwise severed to form a large and small disk segment, with the large disk segment being used to make a sandwich. Finally, not uncommonly, the pita bread may be cut or torn along one circular edge so that the entire pita bread may be filled with edible material to make a larger sandwich.
In the manufacture of pita bread, the components of the bread, basically comprising flour, water, yeast, sugar, and salt, as is known in the prior art, are mixed together in a large hopper. The dough made thereby is then allowed to rise. In some commercial systems the dough is then flattened and is formed or cut, usually on a conveyor system, into the shape of the flattened circular or oval bread product. In other commercial systems, it is rolled into the shape of a ball of dough and then flattened to form a large flat dough disk, like a large pancake. The pita bread in its flattened or circular shape is then allowed to rise slightly. It is thereafter baked in an oven on a flat support surface, typically at a temperature in excess of 500.degree. Fahrenheit. This high temperature baking causes the outer surface of the bread dough to initially sear and thus sealing the surfaces of the dough. The dough in the center of the pita then bakes and, as a result thereof, liberates gas and steam from the dough. This gas and steam is entrapped within the seared outer surface thereby creating pressure within the dough so that it inflates. Since the gas is unable to escape, this internal pressure separates the upper and lower surfaces so that the pita bread resembles an inflated balloon. The inflation continues until the pita ruptures at its weakest location and the steam and gas created by the baking escape.
After baking, the pita bread is allowed to cool and the pita resumes its flat, pancake-like appearance. However, since the upper and lower surfaces of the pita bread were formed during the baking process, these surfaces remain distinct and separate.
A common use for pita bread is the formation of a sandwich. Typically, a user will tear the pita bread in half, forming two semi-disks of dough. These semi-disks will have a relatively straight edge on one side, exposing the two distinct layers of the pita bread, and will have a sealed semi-circular remaining edge. The user can then separate the layers along the torn or cut straight edge and spread these layers, forming a pocket with the pita bread half. Edible material such as meats, cheeses, etc, may be stuffed into the open pocket to form a sandwich. One reason for the popularity of this type of pita sandwich is the fact that the pita bread half forms a natural pouch which is relatively durable and thus not likely to spill when the sandwich is eaten, and which also has less bread than more common sandwiches, thus yielding a lower calorie sandwich.
Alternatively, sandwiches are typically formed with pita bread by cutting or tearing the pita bread at locations other than along its diameter. For example, it is not uncommon to form a sandwich by tearing along a cord of the pita disk removed from the diameter to form a large pocket segment and a small pocket segment, the large pocket segment used to make a single, larger sandwich from the pita bread. In addition, it is not uncommon to cut or tear the pita bread along a circular line following a portion of the circumference of the pita bread to make a single, large pocket from the entire pita bread, and thus a large sandwich.
Because the location of the baking-induced rupture in the pita bread is unpredictable, occurring at the weakest surface of the pita bread during the baking process, sandwiches formed in the above described manners virtually always include a rupture. Even when the pita bread is torn in half to make two sandwich pouches, one of these sandwich pouches will include a baking-induced rupture. The rupture may also occur across the tear or cutting line when the sandwich is made, leaving a torn edge at which the stresses induced during the sandwich making process will commonly cause further tearing and an unsightly sandwich. The rupture in the pita bread, of course, provides a location where sandwich filling material can easily leak or fall from the pita bread pocket and also causes a stress concentration point where further tearing of the natural pouch is likely. These undesirable results are a natural consequence of the pita baking process and have reduced, to some extent, the attractiveness of pita bread as a sandwich encapsulater.
An additional disadvantage of typical pita bread is the fact that, unless the bread is cut with a knife, tearing of the pita bread typically creates an uneven edge which follows the weak portions of the bread's surface. This increases the difficulty in making a neat appearing sandwich or pair of sandwiches from pita bread.
A major drawback in the manufacture of pita bread is that during the baking process, as the pocket inside the pita bread expands, the gases contained therein expand an uncontrolled amount thereby causing tears, breaks and crevices in the surface of the pita bread. This tends to cause substantial problems because such tears or crevices create permanent faults in the breads surface which can result in leaks of the food and sauces contained in the pocket after it is stuffed. Obviously, such leaks can be messy if the sauces, unbeknownst to the eater, leak out on the eater's clothing, hands and the like.
This problem of obtaining undesired faults in the surface of the pita bread was addressed in a United States Patent obtained by Goglanian (U.S. Pat. No. 4,597,979). Goglanian describes creating small holes in the surface of unbaked pita bread, preferably along the diameter thereof, so that when the perforated pita bread is baked, additional rupturing occurs on the surface thereof, which rupturing allows the escape of the gases inside the pita pocket. Goglanian also describes a number of devices for the manufacture of the invented pita, generally comprising multiple steps and manual perforation of each loaf.
There are a number of drawbacks to the Goglanian system in that the rupturing of Goglanian's pita is not well controlled. Specifically, the Goglanian perforated pita can rupture anywhere along the entire perforated surface. Moreover, rupturing is unnecessary for the production of perforated pita bread, and probably, as a practical matter, the rupturing does not always occur at the perforated site, or even at all. With regard to this last point it may be appreciated that the application of tiny holes to a major surface comprised of soft and malleable dough will not always be sufficient to define the rupture site. Of course, it would be appreciated by a person of ordinary skill in the art that it is most desirable to make a pita bread where the probable site of rupturing is well defined and certain.
Several patents owned by the assignee of the present application propose several system which are improvements over the Goglanian patent in the method and apparatus for making pita bread. U.S. Pat. No. 4,889,043 discloses an apparatus for making pita bread comprising a conveyor belt for carrying the pita dough in a long flattened sheet thereon, a cylindrical roller having a circular blades on its surface for cutting out the circular flat pitas, and a circular sawtooth blade disposed adjacent and perpendicular to the conveyer so that the blade perforates the pita dough as it is transported past the blade. The method of making pita bread using the aforementioned device is also disclosed.
A similar device is disclosed in U.S. Pat. No. 4,800,807, which discloses the same cylindrical roller with circular blades on its surface, and instead of the circular sawtooth blade, the circular blades have disposed therein along a chord of the circle, a flat sawtooth blade which perforates the pita dough.
In U.S. Pat. No. 4,775,543, a method of making pita bread with a pressure relief hole is described in which one pita bread is overlapped by an adjacent pita bread during the baking process so that the overlapped pita bread does not fully bake, and is therefore weaker than the baked portion thereof. Accordingly, each loaf of pita bread, when baked, has an intentionally weakened area which ruptures as the pocket expands. The area of the rupture is relatively large, the overlap preferably being about 1/2 inch. Also, the area of rupture includes a small portion of an end seam, so that it becomes desrible to cut off the ruptured portion of the pita in order to stuff it, since the ruptured area obviously cannot contain food, particularly liquids, therein.
The present device and process overcome the limitations of the prior art to produce a pita bread having the desirable characteristics of intentional and limited rupturing in a minimized location without the risk of uncontrolled rupturing or no rupturing at all. The present invention is also directed to flat bread generally having tear markers to indicate the location at which the flat bread should be torn and to begin the tear.